Whether a vow should always be about a better good?

❌ Objection 1 : It would seem that a vow need not be always about a better good. A greater good is one that pertains to supererogation. But vows are not only about matters of supererogation, but also about matters of salvation: thus in Baptism men vow to renounce the devil and his pomps, and to keep the faith, as a gloss observes on Ps. 75:12, "Vow ye, and pay to the Lord your God"; and Jacob vowed (Gn. 28:21) that the Lord should be his God. Now this above all is necessary for salvation. Therefore vows are not only about a better good.

❌ Objection 2 : Further, Jephte is included among the saints (Heb. 11:32). Yet he killed his innocent daughter on account of his vow (Judges 11). Since, then, the slaying of an innocent person is not a better good, but is in itself unlawful, it seems that a vow may be made not only about a better good, but also about something unlawful.

❌ Objection 3 : Further, things that tend to be harmful to the person, or that are quite useless, do not come under the head of a better good. Yet sometimes vows are made about immoderate vigils or fasts which tend to injure the person: and sometimes vows are about indifferent matters and such as are useful to no purpose. Therefore a vow is not always about a better good.